Textile machine device



Nov. 12,1957 w J. H. COULLIETTE 72,812,553

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AUDIO OR LbwfFR'EouENcY AMPLIFIER To CLUTCH CONTROL CIR- sun O CAPACWORINVENTOR Nov. 12, 1957 J. H. COULLIETTE 2,812,553

TEXTILE MACHINE DEVICE Filed June 24, 1954 7 SheetsSheet 5 LP. Brake SetQR B girlie L) I Set T 5 10 7 T5 P, 12, I 1" AUDIO OR LOW FREQUENCYAMPLIFIER Fl g- 2 TO BRAKE CONTROL b CIRCUITS INVENTOR Nov. 12, 1957Filed June 24, 1954 J. H. COULLIETTE TEXTILE MACHINE DEVICE 7Sheets-Sheet 6 6% 67 68 v AuoIo OR LOWPIE- SENSING REFERENCE W ,MPUFIERCAPACITOR CAPACITOR TO cLuTcI-I CON- TROL cIRcuITs RE NULL 74 ''g ANDBALANCE R.F. BRIDGE CIRCUIT Z (SEE DETAILnRAw- QUENCY AMPUFIER ING TOBRAKE cou- TROL cIRcuITs 66 RF.- POWER Aumo oscILLAToR s2 63 64 65 66AMPLIFIER POWER AMPLIFIER (PLATE Monu- LATE BY T0 PLATE MODULATE STANTpu- R. F. POWER AMPU- TUDE A' F. PIER 69 SIGNAL) POWER SUPPLY HIGH- LYSTABIUZED 7O SUPPLIES BLOCKS 7 62, 63,64, 65,66,69

70, 7 I, 72. RF. BUFFER AMP- LIFIER STAGE STABLE cRYsTAL OSCILLATORSTAGE 'INVENTOR Nov. 12, 1957 J. H. COULLIETTE 2,812,553

TEXTILE MACHINE DEVICE Filed June 24. 1954 I 7 Sheets-Sheet 7 COAXIALSWITCH RELAY COIL 76 T0 GRID OF RF. BRIDGE BALANCE TO MODULATOR INVENTORAMPLIFIER United States Patent TEXTILE MACHINE DEVICE James H.Coulliette, Chattanooga, Tenn., assignor to Industrial ResearchInstitute of the University of Chattanooga, Chattanooga, Tenn.

Application June 24, 1954, Serial No. 438,985

Claims. (Cl. 19-130) This invention relates to textile machine controlsand has especial reference to mechanism to provide uniform mass per unitlength of slivers, rovings, laps, or the like.

In order to produce a thread or yarn of uniform weight per unit length,it is necessary to have:

(1) A uniform array of fibres, often designated as a sliver, roving, orlap, and

(2) Machines which'will draw and twist the array of fibres fed into themachine.

In various textile operations it is customary to pass slivers or rovingbetween two spaced pairs of rolls, the forward pair rotating faster thanthe rear pair so that a degree of draw or reduction in cross sectionalarea of the array of fibres will occur. In the prior art the rate ofrotation of the rolls has been adjusted manually at frequent intervalsin order to provide draw in proportion to the quantity of materialpassing through the rolls. This attempt at maintaining uniform crosssection or weight per unit length of the fibre array has not beensatisfactory, however, since frequent manual adjustments have beennecessary and the regulation has not achieved a uniform result.

My method for obtaining a uniform array of fibres involves the settingup of a machine to produce a variable draft, and to control this draftautomatically by means of an electronic circuit which will sense anyvariation in the weight per unit length of the array of fibres, andthereupon alter the draft of the array of fibres to maintain the desiredweight per unit length.

It appears that a logical place to introduce my device for the eveningof the array of fibres is at the picker lap winder, or perhaps at thecomber lap winder. In the picker lap winder a continuous web of fibre isfed from the heaters to the winder, while in the comber lap winder anumber of slivers are drawn from cans and combined to form the comberlap which is fed into the winder. In each machine the winder providesfor taking up the lap between a pair of feed rolls, and supplying it ata uniform rate to a take-up reel which is driven at a constantcircumferential speed by an electric motor with appropriate controls. Myevener device is designed to insure that the lap supplied to the winderfeed rolls has a constant and uniform mass per unit length.

My evener device includes two pairs of fluted rolls of which the forwardpair is geared to, or may in factbe, the winder feed rolls. The secondpair of rolls-the drafting rollsis driven through a slipping clutch,such as a magnetic or hydraulic clutch, at a circumferential speedsomewhatless than that of the winder feed rolls. The pair of draftingrolls carries an electro-magnetic brake which is energized by a variablecurrent. The variable 2,812,553 Patented Nov. 12, 1957 braking currentis supplied by an electrical circuit which senses variations in theweight per unit length of the lap and in turn alters the braking and/ orclutching current.

When the drafting rolls are driven through a slipping clutch, thevarying braking and clutching action will result in a varying speed ofthe drafting rolls, and consequently, a varying draft.

For example, if the electronic circuit senses a thin, or light-weightsection in the lap, a signal is fed to the amplifier to reduce thebraking current and increase the clutch current. creased clutch currentallow the drafting rolls to speed up, thereby reducing the draft, andincreasing the weight per unit length of the lap.

Conversely, a thick section would supply a signal to the amplifier toincrease the braking current and decrease the clutch current. Theresulting increased braking current and decreased clutch current willslow down the drafting rolls, thereby increasing the draft, and reducingthe weight per' unit length of the lap.

The required electronic control circuits can be arranged in a variety ofways. The most obvious sensing device is a capacitor in which the lapconstitutes a constantly changing dielectric. Textile fibres have agreater dielectric constant than air. Hence, the capacitance of thecapacitor Will be increased as the weight of fibre between the capacitorplates is increased. If the textile fibre lap is caused to move betweenthe plates of a capacitor which is a component of a balanced A. C.bridge circuit, increasing the amount of fibre in the capacitor willincrease the capacitance of this sensing capacitor. The increase incapacitance will cause a proportionate unbalance of the currents in thebridge. Conversely, decreasing the amount of fibre will cause unbalancein the opposite sense. Coupling the A. C. bridge to an amplifierprovides a means of obtaining a controlled variable current which isused to energize the magnetic brake and/ or the magnetic clutch. Itremains then to adjust the amplification so that the change in draft issufiicient to re-establish the desired mass per unit length in aspecified time interval. This time interval (or amplification) can bestbe determined by experimental observation of the operation of thedevice.

The stability of the oscillator frequency and the amplification of theamplifier are of importance. The ideal condition is that a certaincapacitance of the sensing capacitor will always correspond to a certainvalue of control current. It would be desirable, therefore, periodicallyto introduce in place of the sensing capacitor a reference capacitorcorresponding to the desired mass per unit length lap, and have theamplification automatically adjusted to give the standard brakingcurrent. This procedure would correct for drift both in the oscillatorand in the amplifier simultaneously.

Since the lap winder is stopped at regular intervals to permit removalof the filled reels, it will probably be satisfactory to maintain thecalibrating adjustment of the evener manually. It can be so arrangedthat when the winder is stopped for the removal of a filled reel, astandard capacitor is automatically connected to replace the sensingcapacitor, and the operator can adjust a control knob to reset thebraking and clutching current (read on an ammeter conveniently located)to the standard value. I

in order to overcome the above-mentioned and other The reduced brakingcurrent and in-, V

defects of past practice, it is an object of the present invention toprovide an automatic roving control which will automatically vary thedegree of draw in accordance with the weight per unit length of theroving.

Another object is to provide means for controlling automatically therelative speeds of rolls feeding material therethrough, the speeds beingautomatically changed in proportion to mass per unit lengthof materialpassing between rolls.

A further object is to provide sensing means for determiningautomatically the density of material being moved by rollers or othermechanism.

Another object is to provide sensing means for determining automaticallythe density of material being moved by rollers or other means and toprovide means for automatically changing the density in accordance withdeterminations of said sensing means.

An additional object is to provide a textile machine for regulatingautomatically the draw of slivers, roving, laps, or the like, in orderto produce an array of fibres of substantially uniform weight per unitlength.

Other objects will appear in the specification.

In the drawings:

Figure 1 is a top plan view of my automatic lap density control device,and associated electrical circuits.

Figure 1a is a fragmentary plan view showing sensing capacitor platesmounted between forward and rear pairs of feed rolls.

Figure 2 is a circuit diagram, partly in block form, illustrating theelectrical connections of my automatic lap density control system.

Figures 2a, 2b, and 2c are circuit diagrams showing components andgroups of components of my automatic lap density control system.

Figure 3 is a diagram of a radio frequency bridge circuit employing asensing capacitor, a comparison capacitor, and a relay to switchcapacitor.

Figure 4 is a cross sectional end view showing rounded type capacitorplates.

In Figure 1, take-up reel 1 is driven as follows: belt 21 transmitspower by means of pulley 10 mounted on drive shaft 11 and by pulley 60keyed to shaft 58. Shaft 58 rotates in long pedestal bearing 59 which isscrewed to base 61. Fluted rolls 2 and 3 are keyed to shafts 4 and 5,respectively. Shaft, 4 rotates in pedestal bearings 6 and 8 screwed tobase 61. Shaft rotates in'pedestal bearings 7 and 9 attached to base 61.Gear 56 is keyed to shaft 4. Gear 55 is attached to shaft 5. Gear 57,keyed to shaft 58, meshes with gears 55 and 56. When pulley 60 turns,gears 55 and 56 also rotate. and 55, being meshed with gear 57, turnfluted rolls 2 and 3. Take-up reel 1 is placed to set in the V formed byfluted rolls 2 and 3. When these rolls rotate in the directionindicated, take-up reel 1 rotates in the direction shown, being drivenby the surface friction of reel 1 against fluted rolls 2 and 3. As thesurface of the material on wind-up or take-up reel 1 is the only contactwith 2 and 3, the material will wind up at a constant lineal speed.

Pulley 10 is fastened to principal drive shaft 11 which carries upperfeed roll 12 and isrotatable in pedestal bearings 13 and 14 attached tobase 61. Shaft 11 is connected. to motor shaft 15 through flexiblecoupling 16. Shaft 15 of motor 17 carries attached pulley 18 whichdrives pulley 19 by means of belt 20. Similarly, pulley 10 drives pulley60 through belt 21. Lower feed roll 22 is mounted on shaft 23 which isrotatable in bearings in pedestals 13 and 14. This roll cooperates withroll 12 to feed lap 52 through the rolls. This lap can be continuous inwidth rather than in strips. Gear 24 is fastened to the end of shaft 23and is meshed with gear 25 fastened to shaft 11. These gears are sochosen that the peripheral speeds of both rolls will be approximatelyequal when shaft 11 is rotated and drives gear 24 through gear 25.

Upperroll 26 is carried by shaft 27 which is rotatable Gears 56 r inbearings in pedestals 28 and 29 fastened to base 61. Lower roll 30 ismounted on shaft 31 which is also rotatable in bearings in pedestals 28and 29. Gear 32 is attached to the projecting end of shaft 31 and ismeshed with gear 33 which drives it and which is fastened to shaft 27.This shaft also carries metal rotor 34 of eddy current brake E, thestator windings 35 of which are fastened rigidly in position by means ofattached frame 36 which is bolted to base 61. Conductors 37 and 38 areconnected with brake windings 35.

Shaft 27 passes through a bearing in pedestal 39 fastened to base 61 andcarries attached metal or other conductive cylindrical shell 40 whichsurrounds rotor 41 having attached electro-magnets 42, the windings ofwhich are connected with slip rings 43 and 44 carried by shaft 45 whichis rotatable in long pedestal bearing 46 which is fastened to base 61.Gear 47a is attached to shaft 27 and is meshed with pinion 48:: on theshaft oftachometer or generator 49 which is screwed to frame 36. Theoutput of instrument or generator 49 is led out by conductors 50 and 51.

Slivers or lap 52 may be pulled out of suitable canisters (not shown),or supplied otherwise, and are fed between rolls 26 and 30, and thenbetween rolls 12 and 22, and are then wound around take-up reel 1. Asthe lap is wound around take-up reel 1, the lineal velocity remainsconstant because the surface of the lap itself wound around reel 1 is incontact with fluted rolls 2 and 3, which rotate at constant speed. Anormal difference in velocity is predetermined between rolls 2 and 3 androlls 26 and 30. This introduces a predetermined fixed draw on lap 52.This fixed draw representsthe normal state of the equipment. This drawis caused to vary in accordance with the mass per unit length of roving52. This will be explained in more detail later.

In Figure 1, sensing capacitor 67 comprises lower condenser plate 67ascrewed to insulating block 67c which is attached to pedestal 13, andupper plate 67b screwed to insulating block 67d which is fastened topedestal 14. Lap 52 passes between these condenser plates which may berelatively long or short to suit conditions. An alternate arrangementfor the sensing condenser, located be tween the feed rolls, is shown inFigure la. This arrangement is preferred when the lap is moving at aslow lineal speed as in the case of the picker lap. The arrangementshown in Figure l is preferred when the lap is moving at a relativelyhigh speed as in the comber lap winder.

In Figure 2 the complete schematic diagram of the control circuits isshown. In Figure 2a the portion of the circuit designed to control theexcitation of eddy current clutch 40-41-42 shown. In Figure 2b theportion of the circuit designed to control the excitation ofelectromagnetic brake 3435-36 is shown.

Figure 2c, in block diagram form, shows the power supply and other unitswhich supply signals to the clutch control and brake control circuits.In Figure 3 the circuit for the radio frequency bridge which containsthe sensing element is shown. Other types of brake and clutch may beused, if desired.

In Figure 2c, the radio frequency circuits and audio circuits whichprecede the clutch control circuit Figure 2a, and brake control circuitFigure 2b, are as follows: block diagram 73 contains voltage regulatedpower supplies supplying circuits 62 through 72. Block 72 is a stablecrystal oscillator supplying a constant frequency radio frequency signalto buffer amplifier 71. Buffer amplifier 71 in turn feeds a radiofrequency signal to power amplifier stage 69. Block diagram contains astable audio oscillator feeding a power audio amplifier which is used tomodulate the amplitude of radio frequency stage 6 at a fixed percentage.i

The amplitude modulated radio frequency energy from amplifier stage 69is suitably coupled into a radio frequency bridge circuit 66. In Figure3, sensing capacitor 67 is a capacitor in one arm of radio frequencybridge circuit 66. Reference capacitor 68 is switched in and out of theradio frequency bridge circuit in place of sensing capacitor 67 bycoaxial switch 74 for purposes of comparison and adjustment of thebridge circuit 66. Switch coil 76, when energized, switches contact arm74a from sensing capacitor 67 to reference capacitor 68 whenever themachine is stopped for unloading. Switch 74 is of the low capacitancecoaxial type and is normally closed in the position leaving sensingcapacitor 67 in the circuit. Reference capactor 68 serves to standardizelap size by simultating the reactance of capacitor 67 when element 67has the proper mass per unit length of lap passing through it. Thus,when the machine is stopped for removal of a full reel, theoperator can,from visual indicator 75,- Figure 2a, see if the equipment is in properoperating condition. Switch coil 76 is automatcally energized by thesame switch used to stop processing of lap andthus affords a convenientway to keep check on the quality of the processed material. Visualindicator 75 is a standard D. C. indicating instrument placed acrossload resistor R9 in Figure 2a. It indicates the value of rectifiedsignal fed to the clutch control circuit. Potentiometer 19 is used tocalibrate meter 75.

In Figure 2 two-stage radio frequency amplifier 65 is used to amplifythe bridge error signal from bridge circuit 66. Amplifier 65 is followedby a linear radio frequency detector stage 64 feeding two identicalsignals to audio amplifiers 62 and 63. The error signal fed to audioamplifier 62 from detector stage 64 is amplified and fed to bridgerectifier D. R. 34-56. This signal then is used in controlling theclutch 4041--42 by the circuits shown in Figure 2a. Amplifier 63 in likemanner amplifies the error signal from detector 64 and applies it to thebridge rectifier D. R. 910-11-12. This, in turn, controls the brakingcurrent in brake 34 through 38, Figure 2b.

The circuit of Figure 3 operates as follows: an amplitude modulatedradio signal from power amplifier stage 69 is fed into bridge circuit 66by means of the combination of transformer and switch components 80, 81,82, 83. Coil 80 is mutually coupled to inductors 78 and 79, beingsupplied R. F. energy from winding 83 of transformer T9. Provision ismade for adjustment of the level of R. F. energy fed to the bridge bymeans of tap switch 81 which, through selection of the proper tap onresistor 82, sets the level for the bridge 66.

Bridge arms of unit 66 are non-resonant to the input radio frequencysignal. Windings 78 and 79 are identical. When radio frequency energy iscoupled into the bridge circuit by winding 80, then equal non-resonantvoltages of opposite phase are induced in arms AC and AD. When variablecapacitor 77 is adjusted to have a reactance equal to that of sensingcapacitor 67, equal circulating currents flow in the paths labeled ADBAand ACBA. These equal currents are 180 out of phase, oppose each otherin primary winding 86 of transformer T9 and cancel out, causing nosignal to be developed in winding 86 if the bridge is in proper balance.The bridge will be in proper balance if the reactance of sensingcapacitor 67 is identical to that of variable capacitor 77. If then,after a balance has been obtained by adjustment of capacitor 77, roving,sliver, lap or another material is introduced into the gap between theplates forming sensing capacitor 67, a change in capacitance ofcapacitor 67 occurs because of the change in dielectric material. Thischange in capacitance of capacitor 67 causes the bridge circuit to be inan unbalanced condition. A current will be developed in winding 86 oftransformer T9 (Figure 3) which will be proportional to the capacitancedifference between capacitor 77 and sensing capacitor 67. This currentwill be due to the phase voltage difference caused by a differentvoltage drop across the reactance of sensing capacitor 67. The voltagedrop across path ADB then does not equal the voltage drop across ACB.Defining Co as the capacitance of capacitor 67 with the desired mass perunit length of textile fibre array between its plates, and C9 as thecapacitance of component 67 when the device is in operation, the outputcurrent Io will be proportion to Ct-Co. The difference in capacitancehas a direct relationship to the output current flowing in winding 86 oftransformer T9. The unbalance current in the bridge is coupled throughthe windings of transformer T9 to the grid circuit of the R. F. bridgebalance amplifier 65. This error voltage as fed to bridge balanceamplifier 65 is utilized as previously described.

The sensing capacitor 67, Figure 4, is of special design. The adjacentsurfaces of the condenser plates 67a and 67b are segments of cylinders.This arrangment provides an increase in smoothness of control of theuniformity of the array of textile fibres. The electrostatic lines offorce between the condenser will be somewhat as shown in Figure 4, sothat a dense section in fibre array entering the electrostatic fieldwill produce a gradually increasing rate of change in capacitance untilit reaches the center of the field, and thence a decreasing rate ofchange of capacitance until it leaves the field. Hence, the signalresulting from a change in fibre density will result in a gradual changein draw of the lap, and a greater evenness of the array of fibres willbe obtained.

The following describes the excitation circuits necessary to control theeddy current clutch and eddy current brake used with this invention. Inorder to develop torque, all eddy current equipment requires slipbetween input and output members. The term torque represents the turningeffect of a force applied at a specified distance from the axis ofrotation. The normal units for torque are in foot pounds. The ability ofan eddy current device to deliver a specified torque on the output shaftdepends not only on the size of unit but on the difference in speedbetween input and output members. The discussion which follows explainshow by a change in excitation, the amount of slip, or torque, can bemade to suit load speeds and thus vary the draft on an array of textilefibres.

Referring to Figure l, the clutch input member 41 is driven by aconstant speed motor 17. Input shaft 45 and drum 40 have no mechanicalconnection, the magnetic field set up between elements 40 and 42 beingthe only means of torque transfer. Field coil 42 is energized preferablyby direct current fed through slip rings 43 and 44 and brushes 47 and48. No useful torque is available until a difference in speed existsbetween output and input shafts 27 and 45. The speed of input shaft 45and degree of excitation of field coil 42 both affect the torquedelivered by output shaft 27. Hence, adjustment of the current in fieldcoil 42 controls the speed of output shaft 27. A small speed-indicatinggenerator 49 driven from output shaft 27 is used as a speed governor.The voltage generated .by generator 49 is directly proportional to itsspeed of rotation. This voltage is used to modulate the electroniccontrol circuit and to cause it to furnish current to field coil 42proportioned to loading conditions on output shaft 27, tending tomaintain a predetermined speed. As the speed of output shaft 27 tends tochange with load change, the excitation to field coil 42 is altered tore-establish the proper operating point. The eddy current brakecooperates in a similar manner.

A description of the electronic means of controlling the currentsupplied to the clutch field coil 42 follows: Figure 2a shows the clutchexcitation circuit and Figure 2b shows the brake excitation circuit.Clutch circuit 2a is broken down into five smaller circuits according tofunction as follows:

Section I.Main rectifier power source comprising components T1, V1, D.R. 1.

Section Il.Reference voltage source having components V2, Re, C7, andT281.

Section [IL-Generator rectifier section components R5, R6, R7, C5, 06,V3, T3 (all).

Section IV.Rider wave or phase shift section with components T182, R2,C15.

Section V.-Grid bias section with components Ra, D. R. 2, C3,R-1,C4.

SECTION I Thyratron V1 in cooperationwith transformer T1 rectifies theA. C. current from lines 55. D. R. 1 is a selenium rectifier used,because of the high inductance of field coil 42, to provide adirectional discharge path to maintain smooth coil current during thehalf cycle tube V1, is nonconducting. The magnitude of current flowingin field coil 42 is a function of the potential existing between grid Gand cathode K of tube V1. Making grid G more positive with respect tocathode K increases current in clutch winding 42. The converse is alsotrue. The volt age existing between grid G and cathode K of tube V1 isthe resultant of that supplied by Reference Voltage Section II andGenerator Rectifier Section III; also, Grid Bias Section V and riderwave from Section IV contribute. In addition, a voltage is inserted inseries with the resultant of the above voltages. This comes from thevoltage across resistor R9, which voltage is a function of the errorvoltage from preceding circuits as applied to Bridge Rectifier D. R. 3,4, 5, 6. It is this voltage across resistor R9 that provides thecontinuous and automatic control of the clutch current as determined bythe mass per unit length of lap 52.

SECTION II Section II provides a stable reference voltage for thepurpose of setting the steady state speed of output shaft 27. Thesetting of potentiometer Ra determines this point of operation.

SECTION HI Section III is the generator rectifier section, the rectifiedoutput of which is available across potentiometer R5. It will be noticedthat this voltage is in series with the reference voltage across elementR8, its point of takeoff being from the movable arm on component R5. Aspreviously mentioned, the output voltage, of generator 49 is directlyproportional to the speed of rotation of output shaft 27. This meansthat any change in output speed of shaft 27 as preset by the referencevoltage across potentiometer R8 causes a proportionate change in voltageto be developed across potentiometer R5. Since this voltage is in serieswith the grid bias voltage from Section V, any change in this voltagewill cause a corresponding change in current in clutch field 42, therebyrestoring the output shaft 27 to its intended speed of rotation.

SECTION IV Section IV is the phase shift or Rider Wave Section in whichan A. C. signal is superimposed on the normal grid bias voltage. Thephase relationship between plate voltage and grid voltage is madevariable by means of potentiometer R2 and capacitor C15. A D. C. gridbias which would normally prevent conduction of tube V1 is appliedbetween grid G and cathode K. When an A. C. rider wave is superimposedupon this negative D. C. bias, the positive A. C. peaks will then exceedthe minimum negative bias necessary to prevent conduction, provided theproper phase relationship exists between the A. C. plate voltage and theA. C. rider wave. The plate voltage must be in its positive phase, andthe grid must also be in positive phase with the phase angle such thatthe peak of the positive half cycle in the plate circuit falls withinthe positive half cycle in the grid circuit. The period of plateconduction depends on how soon in the plate current positive half cyclethe grid is able to overcome the normal negative grid bias. The shorterthe period of conduction, the lower the average clutch .current, theconverse being also 'true.

.8 sncrrou v Grid bias Section V rectifies the voltage applied by meansof secondary S2 of transformer T1 and serves to set up initial operationof the circuit so far discussed.

The following controls are used in the setting up op' eration.Potentiometer R2 is a sensitivity control, determining how small avariation in control signal will change the output speed of shaft 27.Potentiometer R4 is a control for setting the slowest speed.Potentiometer R5 is used to manually pre-set speed between the rangedetermined by resistor Ra and potentiometer R4.

The Brake Circuit The brake circuit in Figure 2b is essentially the sameas clutch circuit Figure 2a. The main differences are that no tachometergenerator is used, and rectifier D. R. 13 replaces the vacurn rectifiertube Vs of circuit Figure 2a. Potentiometer R12 is the brake sensitivitycontrol. Potentiometer R11 sets the minimum constant drag on outputshaft 27 by eddy current brake 40-41-42. Po tentiometer R17 sets themaximum braking current. Secondary S1 of transformer T5 feeds bridgerectifier D. R. 91011-12 with an A. C. signal varying in strength withthe mass per unit length of the textile fibre array passing throughsensing capacitor 67. The rectified D. C. output from this bridgerectifier appears across the terminals of resistor R18. This voltage isinserted in series with the reference voltage developed acrosspotentiometer R11. This varying D. C. signal or error voltage incooperation with the bias across potentiometer R14 and the stablereference voltage across potentiometer R17 varies the current flow inmagnetic eddy current brake field 35, which is connected to terminals 37and 38.

The following describes the interaction and cooperation of both brakeand clutch as a combined unit. In observing the polarities of signalfrom rectifier bridges D. R. 345--6 (Figure 2a) and D. R. 9-10-1112(Figure 2b) it will be noticed that the former applies the positive endof the circuit to cathode K, the other end or negative terminal going tothe movable arm on potentiometer Rs. Rectifier D. R. 9--10-11-12 isoppositely poled, the negative end of this bridge rectifier going to themidpoint of transformer filament winding T653, thus placing the negativeend at the cathode K of thyratron V4. The other or positive end connectsto the movable arm on potentiometer R17. With the polarity of thecircuits as indicated, it is apparent that, with equal signal inputs tothe bridge rectifier circuits, current in the clutch winding willincrease when current in the brake Winding decreases, and vice versa.

For an increase in signal to bridge rectifier D. R. 345-6 for the eddycurrent clutch, the grid of tube V1 will be made less negative and theconduction period of tube V1 will increase. This will cause increasedcurrent flow in clutch field 42. The result will be that of increasingthe output speed of shaft 27 by reducing the amount of rotational slipbetween input and output members.

At the same moment that the clutch current increases, the negativelypoled signal from the brake bridge rectifier D. R. 9-101112 will apply anegative signal to the grid G of tube V4. This limits the conductiontime of tube V4 with a resulting decrease in braking current in winding35. By causing a certain amount of normal braking (by adjustment ofpotentiometer R14), the action of brake and clutch can be made apush'pull operation. When a decrease in R. P. M. is called for by thepreceding error signal circuits, a reduced positive voltage appears ongrid G of tube V1, allowing the normal negative bias to reduce theclutch current and, therefore, output torque and speed of shaft 27.While this is happening to the clutch, a decreasing negative orincreasing net .positive voltage appears on grid .G of tube V 1. Thisincreases the brake field current in winding 35 with increased brakingon output shaft 27. By cooperating in this way, a smooth positivecontrol is obtained over'the speed of shaft 27 and thefeed rolls 26 and30 (Figure l) geared thereto. If the speed of shaft 27 is slowed down,more draw for the lap is provided; and if shaft 27 is speeded up, thereis proportionally less draw. Therefore, the draw is automaticallyadjusted by the clutch and brake, under control of the sensing capacitorso that the mass per unit length of the fibre array is substantiallyconstant. This automatic operation is far superior to manuallycontrolled machines.

In the arrangement described above, a capacitative means of sensingvariations in the mass per unit length of the array of fibres has beendescribed. Other means of sensing these variations may be used such asthe variation in transmission of light through the fibre array into aphotoelectric cell. In using this sensing means a photoelectric cellreceiving light transmitted through the fibre array would replacecapacitor 67, and a similar cell receiving light directly from aconstant source would replace capacitor 77. Other sensing means may alsobe used.

What I claim is:

1. In a textile machine, means including two pairs of rolls for movingand stretching an array of textile fibres, cooperating brake and clutchmeans for controlling the rate of rotation of at least one pair of saidrolls to cause varying draw of said array, means for electricallysensing variations in said array, and means associating said sensingmeans with said brake and clutch means to vary the draw of said array inaccordance with determinations of said sensing means, said brake andclutch means being connected with one pair of said rolls to causeincreased speed thereof when the clutch efiect is increased and to causedecreased speed of said one pair of rolls when the brake eifect isincreased, and said associating means including electrical circuit meansresponsive to variations in electrical currents in said electricalsensing means and connected with said brake and clutch means to causeincreased effectiveness of said brake means simultaneously withdecreased effectiveness of said clutch means.

2. In a textile machine, means including two pairs of rolls for movingand stretching an array of textile fibres, cooperating electricallyoperated brake and clutch means for controlling the rate of rotation ofat least one pair of said rolls to cause varying draw of said array,said brake means reducing the rate of rotation of said one pair of rollson increased brake effectiveness and said clutch means increasing therate of rotation of said one pair of rolls on increased clutchefiectiveness, means connecting said brake and clutch means to cause oneto increase in effectiveness when the other is decreased ineffectiveness, means including a capacitance for sensing variations inproperties of said array, and electrical circuit means associating saidsensing means with said brake and clutch means to cause variation of thedraw of said array in accordance with determinations of said sensingmeans, said variation of draw being caused by variation of the rate ofrotation of said one pair of rolls as a result of variable currents insaid electrically operated brake and clutch means produced by variationsin said array affecting said capacitance.

3. In a textile machine, means including two pairs of rolls for movingand stretching an array of textile fibres, means including power meansand electromagnetic clutch means for driving one said pair of rolls,means for rotating the other said pair of rolls, a generator associatedwith said means for driving said one pair of rolls and producing currentin proportion to the speed of said one pair of rolls, electromagneticbrake means associated with :said driving means to reduce the speed ofrotation of said one pair of rolls, sensing means for determiningvariations in properties of said array, said sensing means includingelectrical means producing current in proportion to said variations, andcontrol circuit means including a 1"0 said generator associating saidsensing means with said electromagnetic brake and clutch means forautomatically causing the speed of said one pair of rolls to vary inaccordance with determinations of said array variations by said sensingmeans.

4. The device of claim 3, said brake and clutch means comprising anelectro-magnetic brake and an electromagnetic clutch, and meansassociating said brake and clutch to cause one to become more effectiveas the other becomes less efiective.

5. The device of claim 3, said brake and clutch means comprising an eddycurrent type brake and an eddy current type clutch.

6. The device of claim 3, said sensing means including a sensingcapacitor, a reference capacitor, a radio frequency bridgecircuit'associated with said capacitors, and relay means for connectingeither capacitor into circuit.

7. In a textile machine, means including two pairs of rolls forimparting draw to an array of textile fibres, power means for rotatingone pair of said rolls at predetermined speed and for rotating the otherpair of said rolls at slower speed to produce draw in said array offibres, electromagnetic clutch means for connecting said power means todrive one pair of said rolls, electromagnetic brake means for slowingthe rate of rotation of said one pair of rolls, electrical means forsensing variations in properties of said array of fibres, and electricalcircuit means connecting said electromagnetic clutch means and saidelectromagnetic brake means with said sensing means to make said clutchand brake means responsive in operation to variations in properties ofsaid array of fibres, said variations causing varied current throughsaid sensing means.

8. The device of claim 7, said clutch being connected to disengage whensaid brake is engaged.

9. The device of claim 7, said clutch being connected to engage whensaid brake becomes disengaged.

10. In a textile machine, means including two pairs of rolls forimparting draw to an array of textile fibres, ,power means for rotatingone pair of said rolls at predetermined speed and for rotating the otherpair of said rolls at slower speed to produce draw in said array offibres, a shaft for imparting rotation to one pair of said rolls, anelectromagnetic brake associated with said shaft to reduce the rate ofrotation thereof, an electromagnetic clutch for effectively connectingand disconnecting said power means and said shaft, electrical meansincluding capacitance means for sensing variations in dielectricproperties of said array of fibres, and electrical circuit meansconnecting said clutch and brake with said sensing means to make saidclutch connect the shaft and power means when the brake is ineffectiveand to disconnect the shaft and power means when the brake is applied,said sensing means and electrical circuit means being arranged to causesaid brake to be increased in effectiveness when the sensing meansdetects a density of said array greater than a predetermined value andto cause said clutch to be increased in effectiveness when said densityis less than a predetermined value.

11. The device of claim 10, said sensing means including an elongatedpair of metal plates between which said array of fibres is passed.

12. The device of claim 10, said sensing means including an elongatedpair of metal plates ahead of the forward pair of rolls, said array offibres passing between said plates.

13. The device of claim 10, said sensing means includ ing electroniccircuit means and an elongated pair of metal plates ahead of the forwardpair of rolls, said array of fibres passing between said plates.

14. The device of claim 7, said sensing means including a capacitorhaving a pair of plates of variable spacing to provide a non-uniformfield therebetween through which the array of textile fibres passes.

1 11 15. The device of claim 7, said sensing means including a capacitorhaving a pair of plates between which the array of textile fibres ismoved, the entrance and exit edges of said plates having greater spacetherebetween than an intermediate location between the entrance and exitof said capacitor.

References Cited in the file of this patent UNITED STATES PATENTS T'-'"'t 7' f Riq a dsqv +---,-,-V----- S p 3, 9 Grqb et a1 July 25', 1950Andersen Dec. 26, 1950 Anderson Dec. 26, 1950 Hiensch n Feb. 20, 1951Ingham Aug. 28, 1951 Busby June 9, 1953 Tuek Octv 6, 1953 Tr u itt Mar.2, 1954 Hare June 29, 1954

